Containment of radioactive wastes



y 26, 1966 M. D. NELSON. JR

CONTAINMENT OF RADIOACTIVE WASTES Filed Sept. 27, 1962 MURRELL D.NELSON, JR.

FIG. I. 1';

INVENTOR.

ATTORNEY United States Patent 3,262,274 CONTAINMENT 0F RADIOAQTIVE WATESMurrell 1). Nelson, In, Arlington, Tex., assignor to Mobil OilCorporation, a corporation of New York Filed Sept. 27, 1962, Ser. No.226,581 3 Claims. (Cl. 61.5)

This invention relates to the containment of radioactive matreials. Moreparticularly, it relates to a method and composition for the safe andcomplete containment of high level radioactive wastes.

The processing of radioactive matter produces large amounts ofradioactive wastes. The principal state of these radioactive wastes isliquid. Although the liquid wastes contain nuclides in a smallconcentration, the level of radioactivity may be very high. These wastesare usually stored as a means of disposal. The storage of wastescontaining nuclides which have a long life requires absolute confinementfor extended periods of time, generally between 15 and 20 years.However, in certain cases the period of storage may be centuries induration. The most common means of storage for the disposal of highlevel atomic wastes is the method of complete containment. The method ofcomplete containment of high level radioactive wastes consists instoring the wastes in absolute confinement until all or most of theradioactivity has decayed. The absolute confinement can be obtained bystoring the radioactive Wastes in leakproof shielded containers. Atpresent, the leakproof shielded containers usually are provided byunderground storage tanks having enclosing walls of concreteapproximately 8 feet in thickness with an inner fluidproof liner ofstainless or mild steel. These tanks are surrounded by a second storagefacility, spaced from the first, with means for monitoring theintermediate space to detect the escape of radioactive matter ornuclides. Further, expensive high speed fluid transferring equipmentmust be available at all times to transfer the high level radioactiveWastes from one storage facility to another in case of a leak.

At present, the above complete containment method requires expensivestorage facilities with continuous supervision and maintenance. It isknown to reduce the cost of storage by reducing the amount of the storedradioactive liquid wastes such as by evaporation or other means ofconcentration of the liquid Wastes. However, even the storage ofconcentrated liquids is very excessively expensive.

There is always the possibility with the present method of completecontainment that as a result of an earthquake, or other catastrophe, thecontents of such facilities may escape confinement and migrate toinhabited areas and thereby contaminate them to a high level ofradioactivity.

It would be desirable to confine the radioactive wastes within the earthin conventional cement, especially where the Wastes are solids. However,because of-the danger of formation fluids leaching the conventionalcement, and the loss of fluids from the cement before and after theinitial setting period, the cement-contained radioactive wastes are notdisposed within the earth, but rather are cast in steel barrels or othersmall impervious containers. This method is expensive because of thelarge number of containers which must be disposed usually by dumping atsea.

Radioactive liquid wastes can be confined in certain imperviousgeological structures, such as in voids present within an imperviousformation. However, such storage facilities require a specific type offormation which is free from migrating fluids which can leach the wastesand then escape confinement. In particular, migrational formation watermust be absent. Further, the storage facilities may be ruptured byearthquakes or the like, thereby permitting the radioactive wastes toescape containment.

It is therefore an object of the present invention to provide a new andeconomical method and composition for the complete containment ofradioactive materials to insure the absolute protection of the publichealth for the period of time required for the radioactivity of theradioactive materials to decay to a safe level. Another object of thepresent invention is to provide a means of complete containment of highlevel radioactive wastes that cannot be disrupted by any knowncatastrophe or act of nature. Another object of the present invention isto provide a composition and method for storing radioactive materials incomplete containment regardless of whether the nuclide containingmaterials are fluids, powders, particles of aggregate size, or mixturesthereof. Another object of the present invention is to provide a methodfor the complete containment of radioactive wastes which does notrequire expensive surface storage facilities or special imperviousgeological structures. Another object of the present invention is toprovide a method and a com position for the containment of radioactivewastes by which the radioactive waste may be easily passed into asubsurface storage area where water or other migra-tional formationfluids are present, Without any possibility of the radioactive wastematerial migrating from the storage area. Another object of the presentinvention is to provide for the complete containment in a storage systemof radioactive wastes, in the form of a radioactive material, whichsystem and material avoid the difliculties and expenses suffered byknown methods for the disposal of radioactive wastes.

Further objects of the invention will become apparent from the followingdetailed description, the appended claims, and the attached drawingwherein the same parts will be designated by like numerals in thevarious views.

FIGURE 1 is a vertical section through the earth showing, as anillustrative embodiment, an application of the invention to a cavernformed in a subsurface salt formation; and

FIGURE 2 is a vertical section through. the earth showing, as anotherillustrative embodiment, an application of the present invention tofractures residing in a subsurface formation.

In accordance with the present invention there is provided a radioactivecontainment composition comprising a mixture of an inverted emulsioncement and the radioactive wastes. Further, there is provided a methodof placing such composition into a subsurface storage area for thecomplete containment of the radioactive wastes. Additionally, there isprovided a system for storing the disposed composition and anonmigrational, cementlike radioactive material from which nuclidescannot escape.

The radioactive wastes contained in the mentioned composition mayconsist of nuclide-containing materials such as aqueous solutions,nonaqueous solutions, and other fluids, solids, such as powders andaggregates, and mixtures of such fluids, solutions and solids. The termradioactive wastes as used herein is intended to include all radioactivematerials in a broad sense, but more particularly, in the disclosedembodiments of this invention refers to the radioactive materials formedas the byproducts in nuclear energy processes.

The inverted emulsion cement used in the containment composition is ofthe type having oil as a continuous phase and preferably is basicallythe cement disclosed in the United States patent to Dunlap et 211.,2,878,875, and entitled Cement. This patent is incorporated by referenceinto this description of the invention. The cement of the containmentcomposition is comprised of an emulaaeaam sion and a solids material.The emulsion is comprised of an aqueous medium, principally water, oilas a continuous phase, and a water-in-oil emulsifier in an amount toeffect temporary emulsification of the aqueous medium and oil. Thesolids material is comprised, at least in part, of hydraulic cement. Inthe present invention, the radioactive wastes are combined with thisinverted emulsion cement, preferably as one or more components orportions thereof. Thus, such radioactive wastes may be included ascomponents, or portions of the emulsion, or of the solids material, orboth, depending upon their physical state to form a mixture which is thecontainment composition. In general, the amounts of the radioactivewastes that may be included as one or more of the components of thecement, or portions thereof, will be controlled by the generalconsiderations relating to the proportioning of concrete and to thedilution of cement pastes or slurries. For example, the aqueoussolutions should not dilute the cement to such a degree that theresultant cementitious mass has insuflicient strength and durability tolast for the necessary period of time required for the decay of theradioactivity of the contained wastes. Also, the amounts of the solidsas powders, aggregates, and mixtures thereof, should not be excessive inquantity or in the amounts of fine particle sizes so that the resultantcement mixture is excessively stiff, and as a result is nonpumpable. Theradioactive wastes should not be used in such amounts, when they containprincipally large sizes and amounts of aggregates, that the resultantcementitious mass is lacking in cohesive plasticity, or contains asegregation of ingredients, or is honeycombed. If the radioactive wastesare not aqueous liquids but are oils, or are oil soluble fluids, careshould be exercised to insure that an emulsion can be obtained fromwhich the inverted emulsion cement is prepared. The amounts of theradioactive wastes used with the inverted emulsion cement as components,or portions thereof, should be within the above bounds in order that thebeneficial cementlike qualities of the inverted emulsion cement andsubstantially retained in the containment composition.

In the inverted emulsion cement of the containment mixture the aqueousmedium in the emulsion may be provided by water, aqueous solutionscontaining salts such as calcium chloride or sodium chloride, theaqueous solutions of radioactive wastes containing nuclides as solublesalts or fine particles or powders, and mixtures of such liquids andpowders. Whatever the source for the aqueous medium, sufiicient wateralways must be present in the final containment composition to hydratethe cement.

The oil is the continuous phase in the emulsion employed in thecontainment composition. Preferably, the oil is a hydrocarbon oil.Suitable oils comprise petroleum fluids, crude oil, diesel oil,kerosene, gas oil, distillate oil, and other petroleum oils. Forexample, an oil containing nuclides may be used as the oil in suchemulsion even though it is radioactive providing it has the requiredphysical characteristics to form water-in-oil emulsions common to theother mentioned examples of hydrocarbons. Hereinafter the term oil isused to denote a hydrocarbon oil. Nonhydrocarbon oils may be founduseful. Nonhydrocarbon oils such as vegetable and animal oils may beused. Thus, vegetable oils, such as cottonseed oil, castor oil, rapeseedoil, tung oil, and

linseed oil, may be employed. Animal oils, such as sperm oil and fishoils, may also be employed.

The water-in-oil emulsion may contain between about 10 percent and about75 percent by volume of oil. With amounts of oil below about 10 percentby volume in the mixture of water and oil, difficulty is encountered inobtaining a water-in-oil emulsion. When the amounts of oil are above 75percent by volume of the mixture of oil and water, insufficient watermay be present to properly hydrate the cement so that the strength ofthe set cement is severely reduced. Preferably, the emulsion containsbetween about 20 and 40 percent by volume of oil.

The emulsion also contains a surface-active emulsifier for water-in-oilemulsions. As an emulsifier, an oilsoluble sulfonic acid, or oil-solublederivative thereof, may be employed. Included among suitable oil-solublederivatives of a sulfonic acid are the mono-, di-, and trivalent saltsof a sulfonic acid, and mixtures thereof. By sulfonic acid is meant anorganic compound represented by the formula RfiQO OH, or R-SO H, where,in the formulas, R may be an alkyl, aryl, aralkyl, or alkaryl group.These sulfonic acids are oil soluble. The sulfonic acids are obtained bya reaction between a suitable hydrocarbon and a sulfonating agent, suchas sulfuric acid, sodium sulfite, etc. The hydrocarbon may be in amixture with other hydrocarbons, such as a crude petroleum oil, or ananimal or fish oil, or fat, and the mixture may have been subjected tosulfonation treatment.

Sulfonated hydrocarbons, such as an oil-soluble petroleum sulfonate, oran oil-soluble sulfonated sperm oil, may be used. A satisfactorysulfonated petroleum sulfonate is one having a molecular weight between440 and 470. Asatisfactory sulfonated animal fat is one having amolecular weight between 250 and 600. Particularly satisfactory resultshave been obtained by employing the petroleum sulfonate sold under thetrade name Petronate and by employing the sulfonated animal fat soldunder the trade name Control Emulsion.

Other suitable emulsifiers may also be employed. These emulsifiersinclude sorbitan monooleate, sorbitan sesquioleaite, sorbitan,trioleate, sorbitan tristearate, lecithin, amino propyl tallow amine,polyoxyethylene sorbitol tetraoleate, and polyoxyethylene sorbitolpentaoleate. Mixtures of various emulsifiers may be employed, ifdesired.

The emulsifier may be employed in an amount up to about 10 percent byweight of the emulsion. Preferably, the emulsifying agent is employed inthe amount between 2 and 6 percent by weight of the emulsion.Satisfactory results have been obtained employing the emulsifying agentin the amount of about 3 to 4 percent by weight of the emulsion.

Where the emulsifying agent selected is any particular a derivative ofany particular sulfonic acid, the effect on emulsification will resideprimarily in the particular sulfonic acid from which the derivative wasobtained and the amount used in the emulsion. The reason is that thesulfonic acid, or its derivative, upon orientation at the watcr-oilinterface will react with the calcium ions from the cement present inthe water phase to form the less soluble calcium salt. This produces astable film of the type necessary for wa-ter-in-oil emulsions. The timelapse between preparation and setting of the inverted emulsion cementdepends on this stable film and is proportional to the concentration ofthe emulsifier in the cement. Sodium ions also may be present in theaqueous phase by the addition of a sodium compound such as sodiumchloride or sodium hydroxide.

The addition to the emulsion of sodium or calcium ions is of anotheradvantage in respect to compensating for the variable electrolytecontent of the radioactive wastes. The sodium or calcium ionconcentration in the emulsion may be adjusted, if desired, to maintain aconstant level at a relatively high concentration. For example, theconcentration may be maintained at 3 or 5 percent by weight of thesodium or calcium salt with respect to the aqueous medium employed inthe inverted emulsion cement. Preferably, the calcium salt is calciumchloride and the sodium salt is sodium chloride. The amount of thesodium or calcium ion containing salt may be adjusted to the desiredconstant level and includes, as part of such amount, the electrolytecontent of the radioactive wastes in the containment composition.

a period of time, in some cases up As has been stated, the invertedemulsion cement of the containment composition includes a solidsmaterial which is comprised, at least in part, of hydraulic cement. Whenthe radioactive wastes are powders, or aggregates, or mixtures of both,they may be included in such solids material in addition to thehydraulic cement. By hydraulic cement is meant a cement which will setunder the action of water. Portland cement is generally employed.However, any mixture containing lime, silica, and alumina, and commonlyused as a hydraulic cement, is satisfactory. Inasmuch as hightemperatures may be produced by the decay of the activity of theradioactive wastes, some consideration should be given to using atemperature-resistant hydraulic cement. For example, where theequilibrium temperature of the containment composition in the subsurfacestorage area reaches temperatures in excess of about 250 F., silicaflour or other heat-resistive agents may be used with most hydrauliccements to increase their resistance to heat-produced deterioration.

The amount of emulsion with respect to the amount of hydraulic cement,excluding other solids material, may vary Within the general limits fromas little as 30 parts by weight of emulsion to 100 parts by weight ofhydraulic cement, or it may be as much as 70 parts by weight of emulsionto 100 parts by weight of hydraulic cement. The amounts of the remainingsolids material that can be used in conjunction with the emulsion andhydraulic cement is determined by the general consideration, asheretofore mentioned, relating generally to the additions of fineparticles, such as sand, and aggregate to cement slurries.

In preparing the containment composition the aqueous medium comprised ofwater, oil, and fluid radioactive Wastes may be mixed together with theemulsifier to provide the emulsion, and thereafter, "mixing the emulsionwith the solids material comprised of hydraulic cement and solidradioactive wastes. Where this procedure is followed, it is desirablethat the mixture of the aqueous medium contain the desired amount ofcalcium and sodium ions, if the latter are present, which ions may beprovided by including within the mixture a suitable calcium salt such ascalcium chloride and a sodium salt such as sodium chloride. It ispreferred that the calcium ions are present when the aqueous medium isemulsified into the oil to form the desired emulsion. Other orders ofmixing the ingredients of the containment composition may be used.

Where the amounts of emulsifier employed are less than about 3 percentby weight, difiiculty occasionally is encountered in obtaining anemulsion wherein the oil is the continuous phase. This difficulty can beavoided by first admixing all of the emulsifier with all of the oil.Thereafter, the remaining ingredients are added alternately inincrements to the oil containing the emulsifier. Of course, the invertedemulsion cement may be prepared and then the radioactive wastes added tosuch cement to produce the desired containment composition. In eithermethod, the general considerations regarding preparation of concretefrom cement slurries should be followed.

The containment composition, upon hardening by setting of the cement,provides a radioactive material which is cementlike and from whichnuclides cannot escape. The containment composition prior to setting isreadily transported, usually by pumping, and therefore is well suitedfor use in various methods for the containment of radioactive wastes insubsurface storage areas. For example, the containment composition hasextended thickening and setting times if formulated to set at a hightemperature, and, therefore, there is available a suflicient time forits preparation and transportation to the desired storage area under allcircumstances before it sets. The composition may be pumped or otherwiseconveyed for to 200 minutes, be fore it thickens. The desired emulsionlife at the temperature of the surroundings in which the invertedemulsion mixture is to be placed can be readily controlled by theconcentration of the emulsifier. The containment composition has anegligible fluid loss, i.e., the loss of fluids from the composition toadjacent geological structures which are more permeable before and afterhardening. This property insures the absolute containment of fluidradioactive wastes during the placement of the containment compositioninto the desired storage area. The containment composition is notmiscible with water prior to its setting into the rigid structure of thementioned radioactive material. After setting of the composition, theresultant radioactive material is impermeable to water or other leachingfluids, including petroleum fluids. The composition after setting orhardening is hereinafter denoted as the radioactive material. Theradioactive material has a great compressive strength which prevents thecatastrophic acts of nature destroying its absolute containment of theradioactive wastes. Thus, the advantages of the containment compositioninclude the property of providing for the absolute containment ofradioactive wastes throughout the steps of preparing the composition,transporting it to the desired storage area, and also, after thecomposition sets to a cementlike mass of radioactive material.

The basic method for the complete containment of radioactive wastes in asubsurface storage area comprises a number of steps. These steps includeproviding a passageway from the earths surface to the subsurfaceformation in which the wastes are to be stored, connecting a storagearea in such formations to the passageway, and inserting conveying meansinto the passageway for transporting the containment composition to thestorage area in the subsurface formation. Prior to, contemporaneouslywith, or after these steps, a step of providing the containmentcomposition is completed at a time sufiicient to place the compositioninto the storage area before it sets. Lastly, the steps are practicedfor transporting the containment composition through the conveying meansinto the storage area and maintaining the composition in the storagearea until it sets. This method produces a system for the completecontainment of radioactive wastes in the desired subsurface storagearea.

This method provides many advantages. One advantage is that the earthsformations surrounding the stored containment composition need only toblanket the hazardous emissions from the radio active wastes as theydecay in activity and not provide a specific geological structure toinsure containment of the composition. Secondly, the surroundingformations are warmed by the heat released by the decay of nuclearactivity of the stored radioactive wastes in the containmentcomposition. Thus, where the formations surrounding the storage areacontain petroleum, the heat conducted and radiated from the storedradioactive wastes reduces the viscosity of the petroleum and otherwisemakes it more mobile. As a result, this method and composition may beused to stimulate the production of petroleum. Also, recovery of theheat generated by the radioactivity decay may be effected by positioningheat exchange means adjacent or in the containment composition.

The storage area may be formed in many types of nonunique subsurfaceformations such as salt beds and shale strata. The storage area may beartificial or natural. It may be a void formed in a formation byleaching a salt bed, by fracturing strata, or it may exist as naturalcaverns, crevices, and fissures. Examples of strata containing naturallyoccurring storage areas are sands containing large-sized ungradedparticles and gravels of a predominantly large size which produce largepore openings, cracked or fissured rocks, or limestone formations,caverns, or other voids in strata created in subsurface formations bythe earths stresses. Some of the cavernous limestone formations are ofespecial utility in their ability to receive and store large quantitiesof the containment composition. Various storage areas may be used whereformation fluids, such as water and hydrocarbon fluids are presentbecause of the nonmiscibility of the containment composition and theresultant radioactive material with such formation fluids. In thisregard, the method of the invention even may be used to place thecontainment means on the floor of the ocean in a layer of mud. Otherstorage areas will be obvious to one skilled in the art.

In FIGURE 1 of the drawing there is shown for the purposes ofillustration an embodiment of the invention where the containmentcomposition is being placed into a storage area formed in a subsurfacesalt formation or bed 11. A cavern 13 is formed in salt bed 11 anddisposed a sufficient distance below the earths surface 12 that theemissions from the radioactive wastes stored in the cavern 13 aresubstantially adsorbed. Thus, no emissions escapeto the earths surfaceto become'a" hazard to public health. The cavern 13 may be formed by anysuitable method. For example, in the embodiment of FIGURE 1, the stepsof the method are as follows: the cavern 13 is formed by providing apassageway 14 from the earths surface 12 into the salt bed 11 and thenforming the cavern 13 by conventional water leaching processes. As thenext step, after the cavern 13 is completed, means for transporting aprepared containment composition 15 into the cavern 13 are provided byinserting a conveying means, such as fluid conduit 16, into thepassageway 14. Fluid conduit 16 preferably extends from the earthssurface 12 through passageway 14 and into the cavern 13. It is preferredto cement, or otherwise seal, the conduit 16 into the passageway 14.Fluid conduit 16 may also be used in the leaching process for formingcavern 13, if desired. In another step, the prepared containmentcomposition 15 is conveyed through conduit 16 into the cavern 13 by anysuitable means, such as gravity flow, in the direction of arrow 17.After the composition 15 is in place, the final step of this method isto maintain the composition 15 in the cavern 13 until it sets to asubstantially rigid and nonfiowing mass. This mass is the cement likeradioactive material. The method produces a system that provides for theabsolute containment of radioactive wastes. If de-sired, a quantity ofcement, without any radioactive wastes, may be passed through theconduit 16 to cleanse it of radioactive materials and :to assist inmaintaining the containment composition 15 in the cavern 13. This methodis of advantage in that the high heat conductivity of salt dissipatesthe heat created by the decay of high level radioactive nuclides.Further, solid radioactive wastes of largesized aggregates which canpass through conduit 16 can be readily stored. Of course, the normalprecautions regarding the handling of radioactive wastes should beobserved when practicing the present invention.

In FIGURE 2 of the drawing, there is shown for the purposes ofillustration another embodiment of the invention where the containmentcomposition 15 is placed into a storage area formed by fracturing stratain a subsurface formation.

In this embodiment, the steps of the method are as follows: A storagearea is formed in a subsurface formation 18 disposed at sufficientdistance beneath the earths surface to provide an effective shieldagainst harmful radioactive emissions. The storage area may beartificial fissures, crevices, and other voids, or it may be created byany suitable means such as mining or forma tion-fracturing processes,particularly, hydraulic fracturing. The formation 18 may be a highlylaminated shale which is readily fractured to produce the storage areain the form of a plurality of interconnected fissures.

More particularly, the method of this embodiment includes the steps ofproviding a passageway 19 from the earths surface 12 into the formation18 where the storage area is to be disposed. If naturally occurringstorage areas are present, they also may be connected to the passageway19. As the next step, the fissures 27 are formed by hydraulicfracturing. In general, the passageway 19 contains a conveying meanssuch as casing 21 cemented therein to insure protection to theintervening strata in case of the escape of fluids passing between theearths surface 12 and the storage area. A tubing 22 is positioned withinthe casing 21 and a fluidproof seal means therebetween is provided andmay be obtained by packers 23 and 24. The tubing 22 preferably containsa back pressure valve 25 to insure the maintenance of the containmentcomposition 15 within the storage area against high formation fluidpressures. The prepared containment composition 15 is forced by suitablemeans, such as by hydraulic pumps, not shown, in the direction or arrow26 into tubing 22. The force created by the hydraulic pumping means mustbe sufficient to convey the composition 15through the tubing 22, backpressure valve 25, and to fracture the formation 18 to provide and fillfissures 27. After the composition 15 is disposed in the fissures 27, itis maintained therein by the back pressure valve 25, or by othersuitable means, until it hardens.

If desired, the fissures 27 may be produced by initially using othernoncompressible fluids in hydraulic fracturing of formation 18. In suchcase, it is preferred that such fluids be removed after the fracturingstep and before the containment composition 15 is forced into thefissures 2'7 to secure the greatest possible storage capacity from thefissures 27.

The foregoing method is of especial utility when the formation 18 isshale for the reason that the permeability of such formations is usuallyexceedingly low and readily fractured. This physical characteristicinsures that the possibility of migrational fluids coming into directcontact with the containment composition 15 is slight. This is anothersafeguard in the complete containment of radioactive wastes by thecomposition and method of this invention.

Although the shape of the storage area is shown as a cavern 13 andfissures 27, it is to be understood that the storage area may havevarious other configurations. In particular, the fissures 27 may extendin vertical or in horizontal planes, or in both planes. The composition15 in fissures 27 generally has a large surface in contact withformation 18 for a small thickness and, therefore, large amounts of heatcan be conducted from composition 15 by formation 18 when thecontainment composition 15 incorporates very high level radioactivewastes.

If desired, the formations containing the storage area may be at leastpartially saturated with water to increase its heat conductivity if noformation water is present. As previously mentioned, the presence ofwater or other formation fluids in any amounts, do not effect thecontainment composition because of its inverted emulsion cementcomposition.

From the foregoing, it will be apparent that the containmentcomposition, method, radioactive material, and system of this inventionare well suited to achieve all of the stated objects. There is provideda composition containing radioactive wastes that is readily prepared andwhich can be easily transported in subsurface storage areas. Acementlike radioactive material is produced upon hardening of thecomposition and from which no nuclide-containing materials can escape.The method heretofore described is simple, yet efficient, for providingthe absolute and complete containment of radioactive wastes below thesurface of the earth. Once the radioactive wastes are contained in asubsurface storage area by the composition and method of this invention,a system is produced to which no subsequent maintenance is required.Further, in this system, the radioactive wastes are completely containedfor a suflicient time interval to permit their level of activity todecay to a safe level. Thus, in accordance with this disclosure of thepresent invention, the radioactive wastes may be completely contained ina manner wherein the public health is protected at all times and underall foreseeable conditions.

Having described our invention, it will be understood that suchdescription has been by way of illustration and not by way oflimitation, reference for the latter purpose being had to the appendedclaims.

What is claimed is:

1. A method for the containment of radioactive wastes comprising thesteps:

(a) mixing radioactive wastes; an emulsion formed of an aqueous medium,oil, a Water-in-oil emulsifier in an amount to efiect temporaryemulsification of said aqueous medium and oil; and a solids mediumcomprised at least in part of hydraulic cement to produce a containmentcomposition, said emulsion containing between about 10 and 75 percent byvolume of said oil as the continuous phase, said emulsion being presentin the containment composition in an amount between about 30 and 70parts by weight of the emulsion to 100 parts by weight of hydrauliccement,

(b) passing the containment composition into a subsurface storage area,and

(c) maintaining said composition in said storage area unttil it sets tothereby obtain complete and safe cOntainment of the radioactive wastes.

2. A method for the containment of radioactive wastes in storage areasin subsurface formations which comprises the steps:

(a) providing in the earth a passageway extending from the earthssurface to a subsurface formation in which the radioactive wastes aredesired to be stored,

(b) preparing a storage area in said subsurface formation and connectedto said passageway,

(c) inserting conveying means into the passageway for transportingfluids from the earths surface to the storage area in said subsurfaceformation,

(d) providing a water-in-oil emulsion cement containing the radioactivewastes desired to be stored in said storage area,

(e) transporting the water-in-oil emulsion cement containing theradioactive wastes through said conveying means into said storage area,and

(f) maintaining said water-in-oil emulsion cement in said storage areauntil it sets whereby the radioactive wastes are completely containedin. said subsurface storage area.

3. The method of claim 2 wherein the water-in-oil emulsion cementcomprises:

(a) an emulsion formed of an aqueous medium, oil as a continuous phaseand a water-in-0il emulsifier in an amount to effect temporaryemulsification of said aqueous medium and oil,

(b) a solids medium comprised at least in part of hydraulic cement, and

(c) said radioactive wastes when an aqueous fluid containing nuclidesforming a portion of the aqueous medium, when solids containing nuclidesforming a portion of the solids medium, and when a mixture of aqueousfluid and solids forming a portion of both the aqueous and solidsmediums,

References Cited by the Examiner UNITED STATES PATENTS 2,779,417 1/1957Clark et al. 166-31 2,838,117 6/1958 Clark et a1 166-421 2,878,8753/1959 Dunlap et a1 166-31 2,880,587 4/1959 Hendrix 61-.5 2,986,0075/1961 Shook 61-.5 3,108,439 10/1963 Reynolds et a1 61.5

FOREIGN PATENTS 237,098 1/ 1962 Australia. 1,235,240 5/1960 France.1,243,673 9/1960 France.

CHARLES E. OCONNELL, Primary Examiner. EARL I. WITMER, Examiner. R. A.STENZEL, Assistant Examiner.

1. A METHOD FOR THE CONTAINMENT OF RADIOACTIVE WASTES COMPRISING THESTEPS: (A) MIXING RADIOACTIVE WASTES, AN EMULSION FORMED OF AN AQUEOUSMEDIUM, OIL, A WATER-IN-OIL EMULSIFIER IN AN AMOUNT TO EFFECT TEMPORARYEMULSIFICATION OF SAID AQUEOUS MEDIUM AND OIL, AND A SOLIDS MEDIUMCOMPRISED AT LEAST IN PART OF HYDRAULIC CEMENT TO PRODUCE A CONTAINMENTCOMPOSITION, SAID EMULSION CONTAINING BETWEEN ABOUT 10 AND 75 PERCENT BYVOLUME OF SAID OIL AS THE CONTINUOUS PHASE, SAID EMULSION BEING PRESENTIN THE CONTAINMENT COMPOSITION IN AN AMOUNT BETWEEN ABOUT 30 AND 70PARTS BY WEIGHT OF THE EMULSION TO 100 PARTS BY WEIGHT OF HYDRAULICCEMENT, (B) PASSING THE CONTAINMENT COMPOSITION INTO A SUBSURFACESTORAGE AREA, AND (C) MAINTAINING SAID COMPOSITION IN SAID STORAGE AREAUNTIL IT SETS TO THEREBY OBTAIN COMPLETE AND SAFE CONTAINMENT OF THERADIOACTIVE WASTES.